Interpretive Summary: Consumption of ready to eat (RTE) minimally processed food has increased over the last several years due to a more health-conscious consumer and a fast-paced society. RTE meats such as ham and bologna are popular among consumers. However, many RTE products can adversely affect microbial food safety because they are usually consumed without additional cooking. RTE food products have been involved in numerous foodborne illness outbreaks. The results of the present study show that, in general, films prepared at WRRC with carvacrol exhibited stronger activity against L. monocytogenes than did cinnamaldehyde-containing films. Inactivation by apple films was greater than by carrot or hibiscus films. Films were more effective on ham than on bologna. To our knowledge, this is the first report on edible antimicrobial films prepared from commercial carrots and freshly harvested hibiscus hips. The results of the present study extend our related previous findings on the efficacy of edible antimicrobial apple films on the survival of L. monocytogenes and E. coli O157:H7 on meat products. Our studies provide a scientific rationale for large-scale application of edible fruit- and vegetable-based antimicrobial films on foods to improve microbial food safety.

Technical Abstract:
Edible films can be used as wrapping material on food products to reduce surface contamination. The incorporation of antimicrobials into edible films could serve as an additional barrier against pathogenic and spoilage microorganisms that contaminate food surfaces. The objective of this study was to investigate the antimicrobial effects of carvacrol the main ingredient in oregano oil, and cinnamaldehyde, the main ingredient of cinnamon oil, incorporated into apple, carrot and hibiscus based edible films against Listeria monocytogenes on contaminated ham and bologna. Ham or bologna samples were inoculated with L. monocytogenes and dried for 30 min, then surface wrapped with edible films containing the antimicrobials at various concentrations. The inoculated, wrapped samples were stored at 4 °C were taken for plating and enumeration of survivors at Day 0, 3 and 7. Carvacrol films showed stronger activities than cinnamaldehyde films. Compared to control films without antimicrobials, films with 3% carvacrol induced 1-3, 2-3 and 2-3 log reductions on ham and bologna at day 0, 3, and 7, respectively. Corresponding reductions with 1.5% carvacrol were 0.5-1, 1-1.5 and 1-2 logs, respectively. At day 7, films with 3% cinnamaldehyde reduced LM population by 0.5-1.5 and 0.5-1.0 logs on ham and bologna, respectively. Inactivation by apple films was greater than that by carrot or hibiscus films. Apple films containing 3% carvacrol reduced the listerial population on ham by 3 logs on day 0 or 1-2 logs greater than by carrot and hibiscus films. Films were more effective on ham than on bologna. The food industry and consumers could use these films to control surface contamination by pathogenic microorganisms.